AFTrainerGuy is correct on the slots being turned in...take the TBAS and go forth with AFRC. Also, the AF doesn't give much credit for a lot of civilian flying. I think 200 hours is about the max for PCSM credit. AFPC has a public site outside of the .mil firewall at:
http://access.afpc.af.mil/pcsmdmz/index.html that explains a lot of this for those looking to go the flying route. Both AD and ARC have "UFT boards" each year (several times a year for ARC, I think) for those officers currently serving in other AFSCs. Good luck to your son!